Assistant Professor Tang Hong-Wen, the study's lead author from Duke-NUS's Cancer and Stem Cell Biology Program, explained the discovery plainly:

"Exercise can reverse this process, correcting the imbalance. Physical activity activates certain proteins which lower DEAF1 levels, bringing the growth pathway back into balance. This allows aging muscles to clear out damaged proteins, rebuild themselves properly, and help them stay stronger and more resilient."

In short, exercise triggers an internal cleanup crew. The findings may also explain why some older adults respond better to exercise than others.

What did the experiments show?

The team tested the mechanism in fruit flies and older mice — two very different species.

The pattern was consistent. Raising DEAF1 levels weakened muscles rapidly. Lowering DEAF1 restored the protein balance and brought muscle strength back.

Because the effect appears in both flies and mice, the researchers believe DEAF1 is part of an evolutionarily conserved system — one that evolution has maintained across species. The experiments also showed causation, not just correlation: changing DEAF1 directly changed muscle function.

A caveat matters here. The experiments involved flies and mice, not humans. Whether the mechanism works identically in people remains unproven, and the researchers frame human applications as eventual possibilities, not established treatments.

Can the benefits of exercise come in a pill?

The discovery may reach beyond ordinary aging. DEAF1 also affects muscle stem cells — the specialized cells that repair and regenerate tissue after injury. These cells lose effectiveness with age, and DEAF1 disruption may worsen that decline.

That makes DEAF1 a potential drug target. In theory, adjusting its activity could mimic some of the molecular changes exercise normally triggers, helping people who can't exercise — patients recovering from major surgery, serious illness, or conditions such as cancer.

Priscillia Choy Sze Mun, the study's first author and a research assistant at Duke-NUS, put it this way:

"Exercise tells muscles to 'clean up and reset.' Lowering DEAF1 helps older muscles regain strength and balance, almost like hitting the rewind button. With millions of older adults at risk of muscle decline, understanding DEAF1 could lead to new ways to protect muscles and improve quality of life."

That future is distant. Researchers still need to establish whether manipulating DEAF1 is safe and effective in humans.

What's the takeaway?

The study draws a sharp line between merely stimulating muscle growth and actually maintaining the systems that keep muscle healthy. Producing more proteins doesn't help if damaged proteins keep accumulating. Both processes must work together.

Professor Patrick Tan, Senior Vice-Dean for Research at Duke-NUS, said the findings "may lead to new ways in which the benefits of exercise can be brought to societies with rapidly aging populations."

The work was funded by Singapore's Ministry of Education, the National Medical Research Council, and other Singapore research bodies.

For now, the message is simple. Exercise still works, and this study explains — at the molecular level — why. But its benefits depend on a delicate protein network inside muscle cells, and understanding that network could one day help those whose muscles no longer respond to a workout.

By Elena Vasquez